A Statistical Examination of the Worm Egg Count Sampling Technique for Sheep

Hunter, Gordon; Quenouille, M. H.

doi:10.1017/s0022149x00032600

Cited by 62 publications

(22 citation statements)

References 6 publications

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“…The distribution of a parasite within a given habitat is also determined largely by its life cycle, resulting in either a random or clumped distribution of infected mammalian hosts in the relevant woodland areas. Lewis ( 1 9 6 8~) indicated that the frequency distribution of parasite numbers in Apodentus sylvaticus from Wales was represented by a negative binomial, which was confirmed in other hosts by Hunter & Quenouille (1952) and Williams & Harris (1965). Such a distribution, unlike a Poisson distribution, suggests that the infective stages tended to be aggregated or clumped rather than randomly distributed within a given habitat.…”

Section: Discussionmentioning

confidence: 85%

A study of the internal parasites of small rodents from woodland areas in Surrey

Lewis

Twigg

1972

Journal of Zoology

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With 3 figures in the text)The occurrence of helminth parasites and leptospires from the Long-tailed field mouse, Apodemus sylvaticus, the Bank vole, Clethrionomys glareolus and the Short-tailed vole, Microtus agrestis has been studied from four woodland areas in Surrey. The composition of the helminth fauna of these rodents, particularly A . sylvaticus and C . glareolus, differs from that of previous studies carried out in the British Isles in consisting largely of cestodes and fewer species of digeneans and nematodes. On the other hand the degree of infection of the rodents with nematodes as in the case of A . sylvaticus infected with the trichostrongylid Nematospiroides dubius and the oxyurid Syphacia stroma and of C. glareolus with the capillarid Capillaria muris sylvatici is greater than the cestode and digenean infections and is probably linked with the monoxenous nature of the nematode life cycles.Differences in the number, incidence and degree of infection of mice and voles with species of helrninths is undoubtedly linked with differences in the feeding habits of the respective hosts but the present study has also confirmed that infection levels in both leptospires and helminths are influenced by the agelsex relationships of the host together with season and habitat. The relationship between the distribution of rodents infected with leptospires and some helminths suggests similarities in the mode of their transmission.

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Section: Discussionmentioning

confidence: 85%

A study of the internal parasites of small rodents from woodland areas in Surrey

Lewis

Twigg

1972

Journal of Zoology

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“…In that case the spacing of repeated observations would be of importance. An aspect of this problem is treated by Hunter & Quenouille (1952)]. Although a greater body of data would be required to produce accurate estimates, it is evident from an inspection of Table 4 that the unrelated calves approach their theoretical maximum efficiency much more rapidly than the twins.…”

Section: Methodsmentioning

confidence: 99%

The value of repeated observations in biological sampling

Boyne¹,

Greig²

1956

J. Agric. Sci.

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1. By separating the sources of variability in an experiment involving haematological observations it has been shown how to estimate the usefulness of repeated observations on each animal.2. In the illustration provided it is concluded that when monozygous twin calves are used, random variability accounts for so much of the total variability that a great improvement in accuracy can be achieved by taking repeated observations on each animal. When unrelated calves are used, little additional accuracy is obtainable by taking more than about three observations on each.3. It is shown that, in consequence, the relative efficiency of monozygous twin and unrelated calves is likely to vary, depending upon the number of observations on each animal. Thus, to benefit fully from the increased efficiency offered by monozygous twins, more observations are required on each animal than in the case of unrelated animals.4. Although the figures refer to haematological measurements on calves, the statistical method evolved is of wider application.

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“…Southwood (1966) explains that k values derived from animal population sampling are often in the region of 2; when higher they denote less clumping and when lower they denote more, these trends leading the negative binomial respectively towards the Poisson and the logarithmic series. Table VI shows k values (k 0 of Southwood, 1966) all of less than 0-5, illustrating the high degree of clumping characteristic of parasitic populations (vide Hunter & Quenouille, 1952;Crofton, 1971a, b).…”

Section: Description and Interpretation Of Infestation Frequency Distmentioning

confidence: 98%

The association between larval parasitic water mites (Hydracarina) and Anopheles implexus (Theobald) (Diptera, Culicidae)

McCrae

1976

Bull. Entomol. Res.

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The parasitic larvae of two species of water mites were studied on resting and biting Anopheles implexus (Theo.) from the Zika Forest near Entebbe, Uganda. Details are given of the mites' morphology, positions of attachment, growth stages and visible effects on hosts. Living larvae of the more numerous mite species (designated as species F, Limnesiidae) were only moderately reliable indicators of the nulliparous state of female hosts, whereas those of the other species (species G, Arrenuridae) were more reliable nullipar indicators, evidently owing to their far more rapid development. The presence of living larvae of either species not completely full-grown denoted the nulliparous state of female hosts with certainty. Male mosquitoes showed consistently lower infestation rates than females from the same resting samples, but the incidence of the different growth classes of species F indicated that these mites departed from hosts of either sex with equal facility and therefore regardless of whether the hosts returned to oviposition sites or not. Frequency distributions of species F on each host sex fitted most closely to highly clumped negative binomials, and biological interpretation of patterns of decline in mite numbers on females in successive Sella's stage groups, and other data, provided evidence of there being at most a negligible amount of mite-mediated host mortality.The study confirms the usefulness as well as the limitations of the presence of parasitic water mites as a rapid means of age-grading female mosquitoes, and suggests several new applications.

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A Statistical Examination of the Worm Egg Count Sampling Technique for Sheep

Cited by 62 publications

References 6 publications

A study of the internal parasites of small rodents from woodland areas in Surrey

A study of the internal parasites of small rodents from woodland areas in Surrey

The value of repeated observations in biological sampling

The association between larval parasitic water mites (Hydracarina) and Anopheles implexus (Theobald) (Diptera, Culicidae)

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